Pneumatically-activated pumps are known and used for metering a desired amount of a lubricant or other fluid from a source to a tool or machine. One type of pneumatically-activated pump is an air tool lubricator that is used to deliver precise amounts of a lubricant, typically an oil, to an air tool. The air tool lubricator is coupled to an air line upstream from the air tool and senses air flow when the tool is cycled, whereupon the lubricator injects a precise volume of lubricant into the airline. The air stream in the air line then carries the lubricant to the air tool. An example of such an air tool lubricator is found in U.S. Pat. No. 4,450,938 (Davenport). The device disclosed therein has a single ball check design that deposits oil directly into the air line.
In other lubricators, such as the Servo Meters.TM. lubricator (Master Pneumatic-Detroit, Inc.), air pressure on a piston pushes a metering pin into a bored hole a preset distance which forces the lubricant through a check valve and into a lubricant line. A ball check valve is used at the air tool so that the lubricant line remains filled with lubricant. A drawback of these lubricators is a tendency to entrap air within the device which reduces their precision.
While the above-mentioned, prior-art devices are functional, they are not completely satisfactory. In particular, presently available pumps can deliver either too little or too much lubricant to a desired location or device. In addition, presently available devices are undesirable because they require the use of a pre-filled lubricant line. Lubricant lines are problematic because they must be carefully filled in order to avoid introducing air bubbles into them. Further, lubricant lines may also leak when not in use, for example, when lines are shipped from the factory to the end user.
In addition to the problems associated with lubricant lines, available pumps are not as useful and adaptable as they could be because of present reservoir design. Typically, lubricant pumps are coupled to reservoirs that hold a desired amount of lubricant for delivery to the pump. Most commonly, the reservoir is separated from the lubricant pump and a conduit, tube, or other connector is used to transport the lubricant from the reservoir to the pump.
More recently, pumps have been designed with a reservoir directly coupled to the body of the pump. One example of a pump having an integral reservoir is shown in Applicant's pending application Ser. No. 08/514,967, which is hereby incorporated by reference herein. Integrally combining the pump and reservoir permits a priming mechanism to be designed into the pump for purposes of pre-filling the lubricant line. However, the pump, reservoir and priming mechanism shown in Applicant's co-pending application are not ideal for all situations. First, the pump is relatively complex and requires numerous components including several valves for controlling air and liquid flow. Second, the reservoir is directly coupled to the pump and, thus, its size and capacity cannot be changed. While this is not a problem in many instances, there are some situations where it would be desirable to use the same lubricant pump in different applications, some of which meter a relatively high volume of lubricant and others which meter a relatively low volume of lubricant. In high volume applications, a reservoir may be rapidly depleted of lubricant and require frequent refilling. In low volume applications, the lubricant may be used too slowly, allowing the lubricant to eventually become degraded over time. Thus, different sized and designed reservoirs will be useful with lubricant pumps.
Another disadvantage of presently designed pumps with integrally attached reservoirs is that maintenance and cleaning of the pumps is difficult in that the reservoir often has to be completely disassembled in order to conduct maintenance and cleaning tasks.
Thus, it would be desirable to have a pneumatically-activated pump that employs a reservoir for containing liquid that can be easily filled with liquid prior to or after being attached to the pump, and can be readily removed from the pump after use or interchanged with a second reservoir containing a different volume and, perhaps, different types of liquid. It would also be useful to have a pneumatically-activated pump with a simplified design that eliminates multiple air and fluid passages and the accompanying valves for controlling air and liquid flow. It would be further desirable to have a pneumatically-activated pump that can deliver a more precise amount of lubricant. It would also be desirable to have an air tool lubricator that does not require a pre-filled lubricant line.